The present invention relates to an intake manifold for an internal combustion engine.
As is known, an internal combustion engine comprises a number of cylinders, each connected to an intake manifold by means of a respective intake valve, and to an exhaust manifold by means of a respective exhaust valve. The intake manifold is connected to each cylinder by a respective intake pipe, and receives fresh air (i.e. outside air containing approximately 20% oxygen) by means of a throttle valve adjustable between a closed position and a fully-open position; and an exhaust pipe extends from the exhaust manifold, and terminates in a silencer to discharge the combustion gases into the atmosphere.
Cyclic opening and closing of the intake valves prevents continuous mass flow of the intake air, and pulsation or even return flow inside the intake pipes occurs. This discontinuous flow impairs charging of the cylinders (and therefore engine torque) and subjects the intake manifold to mechanical stress which prevents the manufacture of lighter-construction intake manifolds.
DE-3210239-A1 describes an air vessel for compensating flow rate fluctuations in pressure lines of pumps and the like (especially oscillating positive displacement pumps); the air vessel has a tubular membrane through which the flow medium flows; a reservoir fluid surrounding the tubular membrane in a housing containing the tubular membrane; a feeler valve located on the outer face of the tubular membrane, in the reservoir fluid; and a pressure vessel containing the reservoir fluid. In this air vessel design, the flow medium flows through the vessel in a straight line; and the tubular membrane is preferably a double tube to prevent the flow medium coming into contact with the reservoir fluid of the pressure vessel.
U.S. Pat. No. 5,826,554 describes pressure relief means for a thin-wall air intake pipe for an internal combustion engine; a valve is installed in an opening in a thin wall of an air intake pipe, which supplies combustion air from a flow control device to an internal combustion engine cylinder, to relieve excess pressure in the pipe. The valve includes a socket connected to a segment of the air intake pipe, and an elastomer, umbrella valve member is supported in the socket to normally cover the opening in the pipe, and to undergo deformation, when the pressure in the pipe reaches a predetermined value, so as to uncover the opening and connect the interior of the pipe to the ambient atmosphere.